This invention relates to a disposable diaper that is used to absorb and contain excretion discharged thereon.
Open-type disposable diapers which comprise a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed between these sheets so as to define a front waist region, a rear waist region and a crotch region extending between these waist regions are well known. In such diapers, a pair of end flaps extends outward in the longitudinal direction from longitudinally opposite ends of the core in the front and rear waist regions.
Furthermore, in such diapers an elastic member associated with a waist-opening and being stretchable in a transverse direction is attached under tension to the end flap at least in the rear waist region. Additionally, elastic members associated with leg-openings and being stretchable there along are attached under tension to the respective side flaps. The core comprises a mixture of fluff pulp, high absorbent polymer particles and thermoplastic synthetic resin fibers compressed to a desired thickness. In such an arrangement, the core has stiffness higher than that of the topsheet and backsheet. Such a well known diaper is exemplified in Japanese Patent Application Publication Nos. 1996-154973A, 1996-317950A and 1996-322876A.
In such diapers the end flaps usually have a stiffness that is lower than that in the region of the diaper containing the core. As a result, the contraction of the elastic member associated with the waist-opening may cause a plurality of wrinkles to be formed over substantially entire regions of the end flaps. Alternatively or in addition, movement of the diaper wearer""s body may distort the end flaps which are partially formed with wrinkles. The portions of the end flaps which are formed with wrinkles are apt to be spaced apart from the wearer""s skin. Thus an undesirable clearance is generated between the wearer""s skin and such portions of the end flaps formed with wrinkles through which excretion may leak to the outside of the diaper.
This invention provides a disposable diaper in which the end flap is well resistant to shrinkage and there is no anxiety that a clearance might be generated between a wearer""s skin and the end flap.
According to this invention, there is provided a disposable diaper comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed between these sheets so as to define a front waist region, a rear waist region and a crotch region extending between these waist regions, and a pair of end flaps extending outward in a longitudinal direction of the diaper from longitudinally opposite ends of the core lying in the front and rear waist regions.
The disposable diaper further comprises a panel member which is flexible and substantially non-stretchable and attached to an end flap at least in a rear waist region and extends in a transverse direction and has stiffness that is higher than that of the end flap.
According to one embodiment of this invention, an elastic member associated with the waist-opening and being stretchable in the transverse direction is secured under tension to the end flap at least in the rear waist region, and the panel member lies between the end of the core and the elastic member associated with the waist-opening.
According to another embodiment of this invention, the panel member has transversely opposite side portions and an intermediate portion extending between the transversely opposite side portions and the inner surface of the panel member which faces a wearer""s skin curves from the transversely opposite side portions toward the intermediate portion so as to describe circular arcs projecting away from the wearer""s skin.
According to still another embodiment of this invention, the intermediate portion of the panel member is shaped to be convex toward the wearer""skin.
According to further another embodiment of this invention, the panel member is made from foamable polyethylene and has a stiffness of about 0.5 mNxc2x7cmxcx9c150 mN cm as measured by the Gurley Stiffness Test.